Atmospheric and vacuum drum dryer



Ap 1959 G. OVERTON 2,880,523

I ATMOSPHERIC AND VACUUM DRUM DRYER Filed July 18, 1955 2 Sheets-Sheet 1\9 INVENTOR G' L- E N OVERTON by Wl ATTORNEY5 I P" \1959 I G. OVERTON2,880,523 I ATMOSPHERIC AND VACUUM DRUM DRYER I Filed July 18, 1955 2Sheets-Sheet 2 FIG, 3

- GLEN OVEKTOM United States Patent ATMOSPHERIC AND VACUUM DRUM DRYERGlen Overton, Dowagiac, Mich.

Application July 18, 1955, Serial No. 522,437

3 Claims. (Cl. 34-92 This invention relates to a dryer and moreparticularly to a dryer arranged to dry materials selectively undereither atmospheric or vacuum conditions.

It is possible to dry many types of materials either under atmosphericor vacuum conditions with each type of operation having advantages overthe other. For example, atmospheric roller process dry milk is preferredby bakers and many other users while vacuum roller process dry milk canbe satisfactorily used as a substitute for fluid milk. In large plants,it has been satisfactory to provide separate dryers for each type ofoperation. For small plants, however, the cost of providing andmaintaining two dryers has been relatively great and in many casesprohibitive.

It is the general object of this invention to provide a dryer which willefiiciently dry materials under either atmospheric or vacuum conditionsand which can be readily changed over from one type of operation to theother.

This invention may be applied to any type of dryer that could beoperated under either vacuum or atmospheric conditions but isparticularly advantageous when 1 applied to a drum dryer of the type inwhich a rotatable drum is disposed in a housing for contacting materialto be dried with means for heating the drum to form a film of dehydratedmaterial on the surface thereof and with means for scraping thedehydrated material from such a surface. Conveyor means may be providedfor carrying the dehydrated material to a point outside the housing and,to permit operation under vacuum conditions, suitable sealing means areprovided in the conveyor means for preventing venting of the housing tothe atmosphere through the conveyor. Such a dryer may be used for dairyproducts, chemicals, distillery and brewery waste, and for many othermaterials and uses.

According to this invention, means are provided for selectivelyoperating the dryer under either atmospheric or vacuum conditions. Inparticular, evacuating means are provided for coupling the interior ofthe housing to a vacuum source and vent means are provided defining avapor flow path from the housing to an atmospheric stack, such ventmeans being selectively controllable between an operative position inwhich the vapor flow path is opened and an inoperative position in whichthe vapor path is sealingly closed, so that the machine may be operatedas a vacuum dryer.

When operating under atmospheric conditions, it is desirable to providean air inlet to the housing and for this purpose a suitable door may beprovided to the housing below the vent means, the door being selectively.movable between a sealingly closed position with the vent means in itsinoperative position and an open posi- ;tion with the vent means in itsoperative position.

Another specific feature of the invention is in an arrangement by whicha vacuum seal is achieved in the vent path, to achieve eflicient vacuumoperation, but with the path, at the same time, being readily opened foratmospheric operation. In particular, closure means are arranged to besealingly secured to the terminal end of a pipe coupled to the housingand vent means are movable between inoperative position for venting suchterminal end of the pipe to an atmospheric stack with the closure meansremoved and in inoperative position away from such terminal end of thepipe to permit ready installation and removal of the closure means.

Preferably, the closure means comprises a cover arranged to be bolted toan annular flange about the terminal end of the pipe with a gasketdisposed between such cover and the pipe. It is possible with thisarrange ment to achieve a highly elficient vacuum seal. It might benoted that conventional valves could be used for opening and closing thevent path but such valves are very expensive especially when a vacuumseal is required.

According to a still further feature of the invention, the terminal endof the pipe coupled to the housing in space registering relation to oneof a stack and a sleeve is provided having a length greater than thedistance between the adjacent ends of the pipe and the stack, the sleevebeing arranged for telescopic connection with both the terminal end ofthe pipe and the end of the stack. With this arrangement, the sleeve maybe moved away from the pipe to permit installation uf the closure meansfor vacuum operation and, for atmospheric operation, the closure meansmay be removed without interference from the sleeve and the sleeve maythen be moved back into telescopic engagement with the pipe.

This invention contemplates other objects, features and advantages whichwill become more fully apparent from the following detailed descriptiontaken in conjunction with the accompanying drawings which illustrate apreferred embodiment and in which:

Figure 1 is a side elevational view of a dryer constructed according tothe principles of this invention and in condition for atmospheric dryingof materials;

Figure 2 is an end elevational view of the dryer of Figure l; and

Figure 3 is a sectional view taken substantially along line IIIIII ofFigure 1, but illustrating the dryer in condition for vacuum operation.

Reference numeral 10 designates drying apparatus constructed accordingto the principles of this invention. The apparatus 10 comprises a pairof dryer drums 11 and 12 disposed in side-by-side inter-engaged relationin a generally cylindrical housing 13. The drums 11 and 12 arerespectively rotated in clockwise and counterclockwise directions asviewed in Figure 3 from a variable speed drive mechanism 14 outside thehousing 13, the mechanism 14 being driven from an electric motor 15through a belt 16.

Liquid material to be dehydrated is introduced through piping 17 intothe trough defined by the drums 11 and 12 which are internally heatedfrom steam introduced through piping 18 to form films of dehydratedmaterial on the surfaces thereof. The condensate from the steam used toheat the drums 11 and 12 is returned through piping 19.

To remove the dehydrated material from the surface of the drums 11 and12, a pair of b1ades 20 and 21 are positioned for scraping thedehydrated material from the surfaces of the drums 11 and 12, with thematerial falling into troughs 22 and 23. Screw conveyors 24 and 25 carrythe material to a collecting screw conveyor 26 which, in turn, carriesthe material to the bottom of a bucket elevator 27. From the top of thebucket elevator 27, the material is dropped into a hammer mill 28 whichreduces the collected dehydrated material to fine powdery form. From thehammer mill 28, the material drops into a hopper and gate assembly whichincludes an upper vacuum-scalable gate under control of handle and alower vacuum-sealable gate under control of handle 31. When operatingunder vacuum conditions, both gates may be closed and the spacetherebetween evacuated. The upper gate may then be opened to allowmaterial to drop onto lower gate and the upper gate may then be closed,after which the space between the gates is vented to the atmosphere andthe lower gate is opened to deposit the material in a container to becarried away. Thereafter, the lower gate is again closed and the spacebetween the gates is again evacuated.

To allow selectiveoperation of the machine under either vacuum oratmospheric conditions, and for servicing and cleaning of the machine, apair of doors 32is provided on each sideof the housing 13 and doors 33and 34 are provided on the ends ofthe housing 13, the doors 32, 33 and34 all being of the type which can be sealingly closed. For operation ofthe dryer 10 under atmospheric conditions, the interior of the housing13 is vented to an atmospheric stack 35 by means of a pipe 36 connectedto the housing 13, the upper terminal end of the pipe 36 being disposedin spaced registering relation to the lower end of the stack 35 with asleeve 7 coupling the upper end of the pipe 36 to the lower end of thestack 35. The doors 32-34 are opened for operation under atmosphericconditions and air entering therethrough combines with vapors from thedrying operation and passes out through the stack. This operation isfacilitated by the fact that the doors are not substantially above thetops of the drums.

For operation under vacuum conditions, the pipe 35 is coupled to acondenser 38 arranged to be connected to a pump or other vacuum sourcethrough a piping 33. The purpose of the condenser 38 is to condensemoisture from the vapor flowing from the dryer and for this purpose,water is introduced through an inlet 40 to contact the vapor with thewater and condensed vapor being removed through an outlet 41.

When operating under vacuum conditions, it is neces sary to sealinglyclose the path from the pipe 36 to the stack 35. For this purpose, thesleeve 37 is telescopingly connected to the upper end of the pipe 36 andthe lower end of the stack 35, to allow the sleeve 37 to be movedbetween the position such as illustrated in Figures 1 and 2 in which thelower end thereof is disposed within the pipe 36 and an upper positionillustrated in Figure 3 in which the lower end of the sleeve 37 isspaced above the upper end of the pipe 36. In this upper position of thesleeve 37, closure means may be readily installed on the upper end ofthe pipe 36. Such closure means preferably comprises a cover plate 42arranged to be secured by a plurality of bolts 43 to an annular flange44 about the upper end of the pipe 36, with a sealing gasket 45 betweenthe cover 42 and the flange 44.

It will, accordingly, be appreciated that this invention provides adryer which will efliciently dry materials under either atmospheric orvacuum conditions and which can be readily changed over from one type ofoperation to another.

When operated under atmospheric conditions the housing or casing acts asa hood connected to a stack thereby inducing a draft which removesvapors and moisture to expedite the drying operation. When operatedunder vacuum conditions the same housing or casing serves the dualfunction of sealing the dryer from the atmosphere and directingthemoisture and vapors to the stack. The housing or casing thus actuallyenhances the drying capacity of the dryer when in closed or openedpositions.

It will be understood that modifications and variations may be effectedwithout departing from the spirit and the scope of the novel concepts ofthis invention.

I claim as my invention:

1. In a drying machine, a housing arranged to receive material to bedried, a rotatable drum in said housing for contacting the material tobe dried, means for heating said drum and forming a film of dehydratedmaterial on the surface thereof, means for scraping dehydrated materialfrom said surface, conveyor means for carrying the dehydrated materialto a point outside said housing, sealing means in said conveyor meansfor pre venting venting of the housing to the atmosphere therethrough, apipe coupled to said housing independently of said conveyor means, anannularflange about the terminal end of said pipe, a gasket arranged tobe disposed on said flange, a cover arranged to be secured to saidflange with said gasket therebetween to seal said terminal end of saidpipe, andvent means movable between an operative position for ventingsaid terminal end of said pipe to an atmospheric stack with said coverremoved and an inoperative position away from said terminal end ofsaidpipe to permit installation and removal of said cover.

2. In a drying machine, a housing arranged'to receive material to bedried, a rotatable drum in said'housing for contacting the material tobe dried, means for heating said drum and forming a film of dehydratedmaterial on the surface thereof, means for scraping dehydrated materialfrom said surface, conveyor means for carrying the dehydrated materialto a point outside said housing, sealing means in said conveyor meansfor preventing venting of the housing to the atmosphere therethrough, apipe coupled to said housing independently of said conveyor means andarranged for disposition in register'with one end of an atmosphericstackv with a terminalend of said pipe spaced a certain distance fromsaid one end of said stack, closure means for sealingly closing saidterminal end of said pipe, and a sleeve having a length greater thansaid certain distance and arranged for telescoping connection With bothsaid terminal end. of said pipe and said one end of said stack to permitinstallation and removal of said closure means.

3. In a drying machine, a housing arranged to receive material to bedried, a rotatable drum in said housing for contacting the material tobe dried, means for heating said drum and forming a film of dehydratedmaterial on the surface thereof, means for scraping dehydrated materialfrom said surface, conveyor means for carrying the dehydrated materialto a point outside said housing, sealing means in said conveyor meansfor preventing venting of the housing to the atmosphere therethrough, apipe coupled to said housing independently of said conveyor means andarranged for disposition with the terminal end thereof and spacedregistering relation to one end of an atmospheric stack, an annularflange about the terminal end of said pipe, a gasket arranged to bedisposed on said flange, a cover arranged to be secured to said flangewith said gasket therebetween to seal said terminal end of said pipe,and a sleeve having a length greater than the distance between saidterminal end of said pipe and said one end of the stack and arranged fortelescoping connection with said one end of the stack to permitinstallation and removal of said cover and for telescoping relation withsaid terminal end of said sleeve with said cover removed to vent saidhousing to the stack.

References Cited in the file of this patent UNITED STATES PATENTS1,151,417 Stokes Aug. 24,1915 2,110,352 Baker Mar. 8,1938 2,552,360Zichis May 8, 1951 2,602,498 Overton July 8, 1952

